Pwm backlight, code adapted from InfiniTime github pull request 'Add PWM Backlight'

2 files changed, 19 insertions, 3 deletions

diff --git a/src/components/brightness/BrightnessController.cpp b/src/components/brightness/BrightnessController.cpp
index 29de5bb..adcd8c5 100644
--- a/src/components/brightness/BrightnessController.cpp
+++ b/src/components/brightness/BrightnessController.cpp
@@ -1,6 +1,7 @@
 #include "components/brightness/BrightnessController.h"
 #include <hal/nrf_gpio.h>
 #include "displayapp/screens/Symbols.h"
+#include "nrf_pwm.h"
 #include "drivers/PinMap.h"
 using namespace Pinetime::Controllers;
 
@@ -8,8 +9,21 @@ void BrightnessController::Init() {
   nrf_gpio_cfg_output(PinMap::LcdBacklightLow);
   nrf_gpio_cfg_output(PinMap::LcdBacklightMedium);
   nrf_gpio_cfg_output(PinMap::LcdBacklightHigh);
-  nrf_gpio_pin_clear(PinMap::LcdBacklightLow);
-  nrf_gpio_pin_set(PinMap::LcdBacklightMedium);
-  nrf_gpio_pin_set(PinMap::LcdBacklightHigh);
+  nrf_gpio_pin_set(PinMap::LcdBacklightLow);
+  nrf_gpio_pin_clear(PinMap::LcdBacklightMedium);
+  nrf_gpio_pin_clear(PinMap::LcdBacklightHigh);
+  uint32_t out_pins[] = {PinMap::LcdBacklightHigh, PinMap::LcdBacklightMedium, NRF_PWM_PIN_NOT_CONNECTED, NRF_PWM_PIN_NOT_CONNECTED};
+  nrf_pwm_pins_set(NRF_PWM0, out_pins);
+  nrf_pwm_enable(NRF_PWM0);
+  nrf_pwm_configure(NRF_PWM0, NRF_PWM_CLK_8MHz, NRF_PWM_MODE_UP, 10000);
+  nrf_pwm_loop_set(NRF_PWM0, 0);
+  nrf_pwm_decoder_set(NRF_PWM0, NRF_PWM_LOAD_COMMON, NRF_PWM_STEP_AUTO);
+  static nrf_pwm_sequence_t seq;
+  seq.values.p_common = pwmSequence;
+  seq.length = 1;
+  seq.repeats = 0;
+  seq.end_delay = 0;
+  nrf_pwm_sequence_set(NRF_PWM0, 0, &seq);
+  nrf_pwm_task_trigger(NRF_PWM0, NRF_PWM_TASK_SEQSTART0);
 }
 
diff --git a/src/components/brightness/BrightnessController.h b/src/components/brightness/BrightnessController.h
index 31ef40a..b8529d5 100644
--- a/src/components/brightness/BrightnessController.h
+++ b/src/components/brightness/BrightnessController.h
@@ -7,6 +7,8 @@ namespace Pinetime {
     class BrightnessController {
     public:
       void Init();
+    private:
+      uint16_t pwmSequence[1] = {80};
     };
   }
 }